<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

</body>
<script>
    var money = prompt('请输入班长有多少钱')
    if (money >= 2000) {
        alert('请大家吃西餐')
    } else if (money >= 1500 && money < 2000) {
        alert('请大家吃快餐')
    } else if (money >= 1000 && money < 1500) {
        alert('请大家喝饮料')
    } else if (money >= 500 && money < 1000) {
        alert('请大家吃棒棒糖')
    } else if (money < 500) {
        alert('下次把钱带够')
    }
</script>

</html>